You might want to shop around a bit, though, because several of those books are cheaper on Amazon than in the iBookstore: Frank Quitely and Grant Morrison’s Batman and Robin, Vol. 1, is $9.68 on the Kindle, $11.99 on iBooks. Frank Miller’s The Dark Knight Rises and The Dark Knight Strikes Again are $9.99 on Kindle versus $12.99 in the iBookstore. There are a couple of more, and in each case that I saw, Kindle beat Apple, at least on price, and all were readable using the Kindle apps on the iPad and Android devices, so these digital versions are in direct competition with each other.